Just finishing up a thorough stock rebuild on my 'ole trusty 300. Haynes says go one full turn after the push-rod stops freely rotating by hand. That seems kinda excessive to me. I always did it "old school" ........valve cover off, engine running and loosened till I could hear the rockers "tick" then tighten till the tick went away and then 1/4 turn.

I'm in new territory here with this rebuild. Took a set of new lifters, soaked overnight submerged in oil, then used a push rod, one at a time to manually pump each lifter till there was no longer any bubbles out of the oil passage hole. Whaddya think about initial valve adjustment? Haynes' "one entire turn" sure seems like a lot.
Thx all !!!!!!!!!

 

That is the "generally" accepted protocol for adjusting the valves on these engines.

 

What year is your engine? What type of rocker arm studs? Certain years require different methods for adjustment.

 

I didn't see your thread. I started one regarding the same thing. My book not only says one full turn, but to initially tighten until the p.rods can not be rotated by hand. It seems real tight to me too. I tighten to resistance, then tighten 1/4 turn more. I will try one full turn tighter.

I had two life time mechanics both tell me to tighten to resistance, then 1/4 turn more.

 

The truck is a '77. The block casting number tells me the engine was first used in production in 1975. As a dinosaur Ford parts guy (we used 6-8 foot long racks of paper catalogs and some microfiche, not a computer in site). D5TE-6015-AA. D=decade of the 70's, 5=1975, T=truck, E =Design Engineering Office...in this case "engine". 6015 is the basic part part number for an engine block. The suffix AA= no mods or specs change as yet.
The engine is at least a 1975 but could have been in production for many, many years without mods or changes. Likely, it is a 1977 engine. Other things I have found also indicate this is a 1977 production.

Back to the valve adjustment question.......1/4 turn past resistance or, according to Haynes....1 full turn? Any ideas? thanks fellas (and probably ladies too)

 

I thought that all pre 84 heads had adjustable v.trains. But AbandonedBronco confused the heck out of me by saying that unless you have screw in type rocker studs, then you simply torque the nut to spec. Refer to my other thread on valve adjustment.

 

Restorer, just for S&G, I spent quite some time researching the correct adjustment for hydraulic lifters on "stud" type 300's. Seems that Haynes is correct. With the lifter sitting on the "heel" of the cam lobe, go to zero lash (basically when you cant spin the p/rod any longer with your fingers) and NO further. Then 1 full turn. Not 1/4 turn. If you think about it....there really is quite a bit of travel in the plunger inside the lifter. I had a lifter completely dis-assembled a few days ago and I would estimate an easy 1/4 to 5/16 of and inch available travel for the plunger (that's being conservative).

Consider this... keeping the valve train geometry in mind; 1 full turn on the rocker nut doesn't account for nearly that much vertical travel of the push rod. Also you want as much lift and duration on the valve as you can safely get anyway. Hence racing cams.
1/4 turn is gonna give you less lift and duration than 1 full turn will. I certainly wouldn't go any further than 1 full turn because sooner or later your gonna have valves that aren't completely closing, possible valve to piston clearance problems and maybe even a bent push rod. I can tell you that 1 full turn is correct, Haynes is right. Just thought I'd let you know what I found. Michael

 

Well two things......AbandonedBronco is right about the screw in studs. I can't speak to the year (84 and earlier) but I can tell you that if you have studs screwed into the head, hydraulic lifters and your rockers go on first, then a fulcrum slid on, then a self-locking nut...........they are adjustable and again, Haynes is correct. One full turn. I thought about the time I put a cylinder head on it about 8 years ago when I bought it. I went 3/4 of a turn. It ran so smooth that if you were deaf and couldn't see the fan and belts turning; you couldn't tell it was running. Last time I tuned it up I did it "old school, while running. Valve cover off and backing off the nut till I heard the ticking in the valve train. Went till the ticking stopped and 1/4 turn from there....It ran like crap. I'm sticking to "static" adjustment and one full turn.

Oh, I was wrong about the duration. You'll get the best lift possible but no change in duration.

 

Having worked as a free-lance writer, I will say that research can be tricky. Often I have found, by confirming a fact with three sources, facts posted in books to be wrong. So, I suggest we agree to disagree.

Also, I would like to point out a few things: The first is that adjusting the valves while running is a chevy thing. No where have I ever heard of or read about adjusting the 300 valves that way. Maybe that was the problem. The second thing is that zero lash means zero free play, and zero free play/zero lash is when you feel resistance on the p.rod when rolling. I know what Chilton says. How precise is it to 'tighten until you can not rotate it any further?' So the strong guy gets tighter valves? The third thing is that using that method you are first tightening past zero lash (how far depends on your strength, or the amount of oil on the p.rod), and then cranking it another full turn tighter!! That is what bothers me. It seems you are real close to bottoming out and making solid lifters out of your hydraulics!

Several forum members, including myself, use the system I have described in a previous posting, with wonderful results.

It might also be noted that the Chiltons I have is for 64--86 300's. For all of those models it recommends adjusting the valves the way you describe. I know AB has an oem 80 head where you simply torque the rockers to spec. Somehow Chilton missed that detail. That show me that there a measurable amount of research lacking in their book, and leads me to wonder what other details were missed or distorted.

 

Restorer, you cracked me up man "So the strong guy gets tighter valves?" I had to laugh at that one. I don't think we disagree and maybe I didn't explain things properly. By "zero lash" I meant until there is no free play between the rocker arm through to the top of the lifter. Not meaning to say depressing the lifter at all, just more or less zero clearance with the lifter plunger still at the retainer at the top of the lifter. You said earlier in this thread that you were going to try one full turn, did you and how did that work out? No I don't need to transform mine into solid lifters either. I haven't yet adjusted mine, just getting ready to put the engine back in and I'm really curious if you already tried one full turn and did it run smooth? Thanks.
BTW I haven't read Chilton's but sounds to me like exactly what Haynes describes. I bought Haynes because they have pretty darn accurate wiring schematics in the back.

 

I had a new engine, with new Isky cam and kit. In less than 2k miles my oil psi went to 3psi, hot, at idle. I checked the bearings and they were thrashed. Something had gone through the oil. I never found out what it was. The reason I mention it is because when I built engine #2, the shop who made a reground cam for me made the base circles too small and the lifters dropped too far and it sounded like a diesel. So I took the cam out of the original engine, with lifters in order, and installed it in the #2 engine. At start up the lifters click like crazy for about a minute. Yep, Isky's 'anti clatter' lifters. That is why I started looking into v. adjustment. It seems there are many methods for adjusting.

Yes, I tried 1/2 turn. Same result. Since it only happens on start up, it seems like bleed down. I tried diff. filters. No affect. I may try the one full turn before I change out the lifters.

Regarding zero lash: To 'tighten until you can not rotate them', as mentioned in the Chilton manual, is kind of like 'torquing a bolt until it feels tight.' Each person would get a different torque. But I guess with the hyd. lifter it doesn't matter.

 

There is a bit of tolerance built into a hydraulic lifter...the nature of the beast...that isn't there with solid lifters. It could be like other adjustments...say timing. Arbitrary numbers don't cut it...got to adjust to what the engine "likes".

 

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The guy I spoke with this weekend that is doing the headwork on my engine proposed an interesting idea for valve adjustment. He said most have told him he's crazy, but he's been doing it for 20 years and it works perfectly every time. Curious what you all think.

Bring piston #1 to TDC. Adjust all 12 rocker arms JUST until there's no slop between the rocker arm/pushrod/lifter.
Rotate 120° to bring cylinder #5 to TDC, repeat with all 12 rocker arms.

Continue until you've done this to all 6 cylinders.

Done.

No torquing, no quarter turns, etc.

He swore up and down by it. Was curious what you all think about it.

 

I've used this method for applications that don't give me a number to work with. My '95 calls for something like 25lbs of torque, so that's what I do. Older classic cars I've worked on will either give you a feeler gauge reading while the engine is hot to measure between the rocker arm and valve spring... and some other cars calls for this "1 and a quarter" turn type stuff. I'm not too hot on that. I like the method you mentioned for valve train adjustments in motors that don't have a very specific number to set them by.

The 120 degree thing is just to get through the job quicker. you can do it from cylinder 1-6 in order. Usually those tricks were learned by old time mechanics getting paid by the flag hour, and wanting to bust out some adjustments in no time at all. Absolutely nothing wrong with that, and if the home mechanic can learn that same trick, everyone wins.

I learned a neat trick when tuning my '67 MGB GT. To adjust the rockers (it's a four cylinder so 8 rockers) you put the first cylinder to top dead center and adjust the rockers that equal up to the number 8. So you start off on cylinder number 1, rocker number 1, then you move to rocker number 7 and adjust it. Then rocker number 2, with rocker number 6, rocker number 3, with rocker number 5, so on so forth while bringing the cylinders up to top dead center.

I can't use that trick anymore though. I just dropped a 5.0 and T5 in my MG.